178 PRACTICAL BOTANY 



physiological connection between the prothallus and the Fern- 

 plant. 



c. A first leaf, or cotyledon, with an elongated petiole, and 

 bifurcating, expanded, upper part : this usually grows upwards 

 through the depression at the apex of the prothallus. 



d. Between the base of the cotyledon and the foot is the apex 

 of the stem, which continues its growth, and produces new 

 leaves. 



